1. Field of the Invention
This invention relates, generally, to automatic paper hole punches, for preparing paper for binding into a spiral notebook, for example. More specifically, this invention relates to a punch machine that has an improved die assembly and mounting means, allowing the die assembly to be quickly installed and removed without bolts, screws or housing panel removal.
2. Related Art
Many automatic punch machines have been built with die assemblies for punching holes through a stack of papers prior to binding. Typically, these die assemblies are bolted into the machine and can be removed for cleaning, replacement or adjustment only by partially disassembling the machine. Bolts, screws, housing panels, and sometimes other machine parts must be removed to remove and replace the die assembly. Although such punch machines can be built to operate effectively and reliably, maintenance of the die assembly is not quick or easy.
One automatic punch with a bolt-in die assembly is the xe2x80x9cVersa-Punch(trademark)xe2x80x9d, model VP-6000, made by Performance Design, Inc., of Boise, Id. This punch 100 is shown in FIGS. 1A and 1B. This punch machine includes a die assembly with a plurality of punch pins that are forced generally perpendicularly through the paper near the paper edge. The paper is held vertically with its edge inserted into a slot in the die assembly. The punch pins are then driven across the slot to cut through the paper, creating a hole in each paper at the location of each punch pin.
In order to access the die assembly 102 of the Versa-Punch(trademark) machine, the user must unscrew four screws or bolts 104 to remove a top cover 106 and a front cover 108. Then, to remove the die assembly, four bolts 110 must be removed to detach the die assembly from the machine frame and three more bolts 112 must be removed to detach the assembly 102 from the push-bar 114. To replace the die assembly, the procedure is repeated in reverse, with the user having to hold the die assembly in place to align it with the various bolt holes.
The die assembly 102 shown in FIG. 1B is a square-hole design, which includes a die and a pull-back bar that each have square holes and that are connected by stripper bolts and bushings. This die assembly 102 also includes push-pins and square-end punch pins. The push-pins are pushed into bores in the top of the pull-back bar to engage each punch pin, that is, to secure each punch pin in a position in the pull-back bar that will result in punching of the paper.
Another example of a prior art die assembly that may be used in the bolt-in system is illustrated in FIG. 2. This die assembly 102xe2x80x2 typically includes a die 116 with paper slot and die holes, a pull-back bar 118 with holes for receiving a plurality of punch pins 120, and a backup bar 122 screwed onto the pull-back bar for keeping the pins in the pull-back bar. The pull-back bar 118 is connected to the die 116 by means of the stripper bolts. To punch paper, the push-bar 114 drives the pull-back bar 118 forward and backward on bushings on the stripper bolts 126, thus moving the punch pins 120 forward and backward in the die holes 128. The push-bar 114 is supported inside the punch machine 100 only by its attachment to the connecting rods and its being bolted to the die assembly 102.
These die assemblies 102, 102xe2x80x2, and the many other typical assemblies made for various binding coils and combs, each has a uniquely sized, spaced and shaped set of holes which typically are centered along about a 14 inch length of the die that is typically centered between the two ends of the die. Therefore, when the user wishes to punch standard 8xc2xdxc3x9711-inch paper instead of the 14-inch paper, the user must move the paper stop 60 to accommodate the paper and also move the stop each time he/she changes the die assembly. If this adjustment is not made, the punched holes are not centered along the 11-inch paper edge. The holes may be slightly offset to the right or left, and a partial hole may be cut at one or both ends of the paper edge. This results in inferior binding and an unprofessional appearance. For example, as shown with the prior art die assembly 130 of FIG. 7A, the paper stop and left edge of the paper are set at xe2x80x9cSxe2x80x9d for punching the 14-inch paper. When the same paper stop setting is used for 11-inch paper in this same die 130, the holes in the 11-inch paper are not centered and the far right hole 132 extends to or past the 11 inch paper edge. When maintaining the same paper stop position and switching to another prior art die assembly 134, again the holes are centered within the 14-inch length, but punching 11-inch long paper results in the holes not being centered along the 11-inch length and the far right hole 136 being nearly at the paper edge. To properly punch the 11-inch paper with these two dies 130, 134 requires adjustment of the paper stop to a different position than used for the 14 inch paper and to different positions for the two dies.
This invention comprises a punch machine and quick-change die assembly for punching holes in paper or other sheets of material. The die assembly is supported and secured inside the punch machine housing by a lateral slidable connection with the push-bar and by clamp means that may be easily operated from outside the machine housing. The die assembly need not be bolted to the machine frame or the push-bar and may be quickly removed simply by being unclamped, preferably by simply swinging a clamp handle, and slid out of the machine housing.
The invented punch machine also comprises an improved push-bar system for driving the die assembly. The push-bar is slidably supported in the punch machine, preferably by bushings in the side plates of the machine housing. Thus, the push-bar stays in place when the die assembly is removed, so that the die assembly may easily be reinserted without manually moving and aligning the die assembly and push-bar.
The preferred die assembly is simplified in structure compared to conventional die assemblies and comprises a die, pins, and pin retainer (also referred to as a xe2x80x9cpin retainer platexe2x80x9d) that slidably receives the pins, and, in an especially-preferred embodiment, also a moveable pin strap for keeping the pins in place during handling and installation of the die assembly, and a positioning system for optimizing the position of the pins and the pin retainer relative to the die during the installation of the die assembly into the punch machine. When the die assembly is installed in the punch machine, the die and pin retainer are mounted in the machine housing by the clamp(s) and push-bar slot, respectively, with the punch pins extending from the retainer to the die. The push-bar then moves the pin retainer relative to the die, thus, pushing and pulling the punch pins in and out of the die holes.
The die and pin retainer need not be bolted together or connected by any bushings or stripping bolts. However, in the especially-preferred embodiment, the invented positioning system includes a connecting mechanism for connecting the pin retainer to the die, so that the pin retainer will not fall away from the die. The positioning system preferably holds the pin retainer at the desirable distance from the die during handling and installation. The positioning system may be designed to bias the pin retainer out from the die at a set distance (that is, the xe2x80x9cbiased positionxe2x80x9d), which is the distance that is proper for the die assembly to slide smoothly into the machine, with the pin retainer sliding into the push-bar slot and the die sliding into proper clamping position. The positioning system with its biasing system is adapted so that, once the die assembly is installed, it does not interfere with forward and rearward movement of the pin retainer and pins during punching. The positioning system may also be adapted to include a floating feature that allows some leeway in the biased position of the pin retainer (and in the position of the associated apparatus that must slide through the push-bar slot), thus compensating for possible variations in the push-bar location at the time of installation of the die assembly. For example, this leeway may be necessary if wear and/or variations in punch machine construction result in the punch bar being slightly forward or rearward from its xe2x80x9cstandardxe2x80x9d position when the push-bar operation is stopped. The leeway lets the pin retainer, pin heads, pin strap, and connecting mechanism move to match up with the location of the push-bar slot and smoothly slide into place.
The quick-change die assembly also provides a simplified and quick method of changing or rearranging punch pins. When the die assembly is removed from the machine, one or more punch pins may easily backed out from the pin retainer. Many embodiments of the die assembly are adapted so that, once the die assembly is installed in the punch machine, the pins are held in the pin retainer only by the push-bar and preferably without other backing and without bolts.
In the especially-preferred embodiment, however, the movable pin strap, which is normally positioned over the pins during handling and installation of the die assembly in the machine, may be pivoted or otherwise moved aside quickly, easily, and without tools, for assess to the pins. In embodiments having a pin strap, the pins of the installed die assembly are held in place between the pin retainer and the pin strap, with the pin strap being located between the pin heads and the push-bar when the die assembly is installed in the punch machine.
The die assembly preferably also includes a consistently-referenced system of die hole placement, so that the paper stop need not be adjusted each time a different style die assembly is installed. This system is called herein an xe2x80x9cend-justifiedxe2x80x9d system because the 11-inch area at one end of the die has its holes centered within that 11 inch area. This system allows the die assemblies to be more compatible with the preferred paper size, for example, 8xc2xdxc3x9711-inch paper, so that the paper stop need only be changed for the occasional punching of longer or shorter paper.